The present invention relates to hydroelectric assemblies to be incorporated at water storing engineered structures such as gates- fixed weir dams, spillways, navigable passes, beartraps, miter gates, non-utilized lockage structures, etc; for purposes of energy generation or energy accumulation; and more particularly to hydroelectric assemblies adapted to be interchangeably positioned at a plurality of such water storing engineered structures.
Hydromotive assemblies for hydroelectric production plants and more particularly, hydroelectric machines for very low heads and using siphon draft tubes with ascendingdescending flow water circulation paths are, obviously, well known in the art.
The aim of such hydromotive assemblies, archingly positioned over water retaining structures such as fixed crest dams, spillways, gates, etc. is to convert the inherent gravitational energy of the water stored in reservoirs behind these dams into electric energy. The importance of this conversion is particularly significant in low-head hydroelectric stations and in very variable low-head hydroelectric developments which are the most vulnerable to river flow seasonal variable hydrological conditions. In droughts, the water flow is so reduced that nearly all the firm capacity is lost while in floods, the hydraulic head is so reduced that the ability to produce electric power is also lost. The true aim is to develop a more flexible concept to adapt low-head hydroelectric generation stations to all these deterring hydrological situations. This transportable and incorporable hydromotive assembly concept provides the answer to cope with these technical dilemmas
It is also known that in a hydroelectric station, the highest mechanical simplification is provided when technical means for starting and stopping the hydromotive machines avoids the use of gates, valves, and movable distributors. The incorporable hydromotive assembly engineered with the siphon draft tube of ascending-descending flow water circulation path concept, will fulfill this requirement because starting of the hydromotive machine is easily provided by actuation of a vacuum pump which produces air suction within the draft tube with consequent water low level rising and filling of the draft tube, thereby starting a hydromotive turbine automatically without the use of cumbersome gates, valves, or costly movable distributors.
Likewise, stopping of the hydromotive turbine is also easily achieved by actuation of a relief valve which provides air admission into the draft tube, thus producing disruption of the water flow.
Another mechanical simplification concerns the possibility of avoiding expensive tilting pad thrust supporting bearings and replacing them by conventional roller bearings. This possibility is developed because the upwards hydraulic thrust when the machine is in rotation, is nearly balanced by the weight of the rotating parts integrally combined with the turbine runner, the generator rotor and the connecting shaft, thus providing the possibility of installing cheaper roller bearings with consequent reduction in manufacturing costs and simplification in engineered design concepts and maintenance procedures.
The incorporable hydromotive assembly concept provides also a new kind of arrangement by means of which erection costs of expensive civil engineered structures for permitting support of these hydromotives turbines and hydroelectric machines, is simply avoided.
In nearly all the situations, hydropower production will be readily available without construction of concrete structures such as highly expensive and intricate water intakes, scrolls, bends, diffusers, etc.
A very compact arrangement is provided to fulfill this objective. This transportable and easily incorporable hydroelectric assembly can be positioned into a plurality and variety of water storing structures, thus leading to flexible concepts in hydroelectric generation erection engineered procedures.
It is also known that the best hydroelectric station engineered project must be designed under standardized patterns and mass produced industrial components. Furthermore, under operational performance, the concerned hydroelectric station must not have shutdown delays for cause of maintenance procedures on generators and turbines. It must have also, a low investment figure in terms of money expended per kW. of installed capacity.
Additionally, the erection time schedule required to install turbines and generators and put them in operation must be as short as possible.
All these objectives are claimed to be made possible by means of the present invention. These considerations, which not only take into account mechanical simplicity but also financial requirements, have not been fulfilled up to the present time because the technology in low-head hydroelectric generation has not advanced enough in efficient terms to keep pace with the most massive nuclear electric generation development. Consequently, many hydraulic structures designed for non-energy production purposes; and which today could be utilized for hydroelectric production, are inoperative and not being employed in a profitable status.
Because of the inherent simplified mechanical engineered design and cheaper manufactured components together with mass produced interchangeable parts, vertical or slant-axis capsule-mounted generators with fix-bladed propellers, or movable-bladed Kaplan turbines acting as motive machines working with draft siphon tubes having ascending-descending water flow circulation paths, can be expected to be progressively introduced and put into operation in the forthcoming years.
Another object of the present invention is to provide a novel hydrostation engineered arrangement whereby hydraulic structures already built for other purposes such as dams for navigation systems, inoperative locks, abandoned dikes, structures for irrigation intakes, etc. can be easily converted into hydropower generation systems.
A further object of the present invention is to provide a new technique designed to improve actual hydroelectric tactical exploitation procedures by means of incorporable and transportable hydroelectric stations to be readily embodied at such hydraulic engineered structures or moved away from said structures following the changes imposed by the variable hydrological status of the involved rivers.
In other terms, when a river flow decreases due to a drought, these incorporable and transportable hydromotive stations are removed from the inoperative hydraulic structures and transferred to other watersheds having operative hydraulic structures. Inversely, when a flood condition imposes a non-producing hydroelectric status due to head reduction, these transportable and incorporable hydroelectric assemblies are mobilized and reinstalled in other watersheds to be placed in operation once again.
This novelty in low-head hydroelectric generation provides an improved flexible tactical arrangement for purposes of electric generation planning in river watersheds heretofore considered energetically unprofitable and impossible.
According to one aspect of the present invention, there is provided a transportable and incorporable hydromotive assembly for energy transformation purpose which to be installed against the structural body of a dam or related engineered water retaining structure. In the overall general arrangement this incorporable hydromotive assembly is archingly positioned over said dam or engineered structure.
Incorporated is a water conduit or draft siphon tube providing an ascending-descending water flow circulation path, defined by a lateral wall surrounding the hydromotive machine and having a first open end for water admission and a second open end for discharging water entering the first open end. Auxiliary means are provided for purpose of water flow circulation starting and for water flow circulation disruption as is well known in the art.
The incorporable hydromotive assembly is provided with at least one chamber defined in its surrounding engineered structure having a volume at least sufficient to cause sinking or floatation of the incorporable hydromotive assembly when the chamber is filled with liquid or gas, respectively. By providing a plurality of these chambers the sinking or floatation procedure can be accomplished in any desired controlled position of the hydromotive assembly. Means are also provided for filling the chambers with fluid for sinking purposes or with gas for floatation purposes, this means can also be provided from a portable source external from the hydromotive assembly.
Another method for providing controllable sinking or floatation of said hydromotive assembly is by means of incorporable ballast weights positioned around the structural embodiment of the hydromotive assembly. Optionally, this structural embodiment may incorporate a machine hall with all the required mechanical equipment for purposes of operational control of the hydromotive turbine and generator sets such as turbine governors, generator controls, compressed air systems, electric transformers, switching stations, relay systems, emergency energy sources. etc.
According to an even further aim of the present invention there is provided a new conception in engineering design of hydroelectric stations which avoids the machine hall and related powerhouse structures. With this arrangement, maintenance of motive machines is simplified too. Machines which require overhauls are instantly shifted away and replaced by operative ones arriving from the service center. Thus, a unique service station is provided for purposes of maintenance of a plurality of hydroelectric stations, thereby revolutionizing the engineering servicing technology in hydroelectric generation.
For purposes of archingly positioning the siphon draft tube with its ascending-descending water flow circulation path, over the variable transverse embodiment of a plurality of spillways or water storing engineered structures, thus producing the interchangeable condition required to fulfill the required incorporable feature means are provided for adapting the siphon draft tube structure to variable transversely sectionalized spillway profiles. These means are integrated by a variety of technical devices such as movable supports or movable steel plates, jacking arrangements, hydraulic bolting or movable fastening structure, etc. as is well known in the art.
According to an even further aspect of the present invention, a method is provided for incorporably positioning the hydromotive assembly over water retaining structure and archingly securing it into this position. The method comprises the steps of: (a) Taking a hydromotive assembly having a structural body, a first water open end and a second water open end and at least one chamber structurally combined with the body. (b) Floating the hydromotive assembly slightly upstream of the engineered dam water retaining structure and so oriented that the longitudinal axis of the water flow circulation path is substantially perpendicular to the longitudinal axis of the dam, and with the second open end positioned substantially thereabove the crest of said dam. (c) Drawing the incorporable hydroelectric assembly movably towards the dam water retaining structure until the second open end is positioned entirely downstream of the dam water retaining structure. (d) Introducing a liquid into the body chamber to cause sinking of the incorporable hydromotive assembly or alternatively, adding ballast weights to the structural body to cause sinking of the hydromotive assembly. (e) Directing the sinking incorporable hydromotive assembly until it rests slightly on the bottom supporting means or alternatively, until it is archingly positioned over the dam water retaining structure. (f) Securing the incorporated hydromotive assembly in such position.
Although most references in the specification are applied to hydromotive assemblies arranged following the siphon draft tube ascending-descending water flow circulation path system it will be obvious to those skilled in the art that the teachings of the present invention are free of the specific linear layout of said path and that the present invention is applicable to assemblies in which such geometric spatial configuration follows any pattern, such as a substantially rectilinear one.